But he didn’t call her the worst technology chief executive in history. In fairness to Ms. Fiorina, she may not even be the worst chief executive of Hewlett-Packard.

A contender for that dubious distinction would surely be Léo Apotheker.

During their tenures at H.P., both Ms. Fiorina and Mr. Apotheker presided over what were hailed as transformative acquisitions: Compaq, the personal computer company that merged with H.P. in a $25 billion stock swap under Ms. Fiorina in 2002, and Autonomy, a British software concern that H.P. bought for $11 billion in 2011 in a deal overseen by Mr. Apotheker.

They were transformative, all right, though hardly in the way their proponents intended. H.P.’s stock price fell by more than half during Ms. Fiorina’s six-year tenure and by roughly 50 percent in just the year Mr. Apotheker was chief executive. The board forced both Ms. Fiorina and Mr. Apotheker to resign.

The remnants of Compaq will be spun off by H.P., and in 2012 it wrote off $1.2 billion in value of the Compaq brand name. H.P. wrote off $8.8 billion related to Autonomy.

Just how bad is confirmed by the latest revelations from a shareholders’ suit over the deal: Mr. Apotheker didn’t even read the due diligence report on Autonomy that H.P. commissioned from KPMG, the giant accounting firm. Nor did Raymond J. Lane, the board chairman, or any other member of the board, according to a report prepared by the law firm Proskauer Rose, which was hired to represent H.P.’s independent directors.

Had they read even the executive summary, they would have discovered numerous warnings — enough to have prevented the deal in the first place, or at least to have led them to renegotiate it.

“For the C.E.O. not to have read it, for an acquisition this size, is highly disturbing,” said Charles M. Elson, director of the Center for Corporate Governance at the University of Delaware and co-author of “The Art of M&A Due Diligence.” “And the entire board should have at least read the executive summary.”

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Hewlett-Packard has sued Autonomy’s former chief, Michael Lynch, who in turn has countersued.CreditHazel Thompson for The New York Times

Colby A. Smith, a lawyer at the law firm Debevoise & Plimpton who is representing Mr. Apotheker, said, “Neither KPMG nor any member of the finance function nor any member of the board ever raised to Léo’s attention any concern about finances or accounting at Autonomy.”

I’ve read the full report, which was also disclosed in the shareholders’ lawsuit. The executive summary stresses repeatedly that Autonomy stonewalled KPMG accountants, who were granted “access to very limited proprietary financial and tax information,” the KPMG report says at the outset.

“The data and access provided to us during due diligence was very limited,” the report says, which, it adds, is “not unusual” when dealing with acquisitions in Britain.

The report also questions Autonomy’s claimed stellar revenue growth, a critical factor in justifying the exorbitant price H.P. ended up paying: “A significant amount of the revenue growth is due to acquisitions,” the report said. Just how significant couldn’t be determined given Autonomy’s lack of cooperation, but the accountants warned that “organic growth rate has declined at both its core business and overall business.”

While management maintained that growth rates “weren’t impacted by one-time transactions, it was not prepared to provide customer data to validate this statement.”

The report also raised questions about Autonomy’s revenue recognition practices — how accounting for sales was done — although again it noted that without more information, it couldn’t provide answers.

The report concluded, “The lack of access has limited the analysis we could perform.”

The Proskauer report noted that Autonomy and its auditor, Deloitte, had specifically refused to give KPMG access to its work papers, even though a top executive working on the deal at H.P. had identified those papers as a “must have.”

I’d say that for $11 billion, H.P. should have been able to see whatever it wanted.

What H.P. directors did get before approving the deal was a one-page “management summary,” which dismissed the KPMG due diligence report with one sentence: “No material issues found.”

An H.P. spokesman said it wasn’t clear who prepared that summary but noted that at least six H.P. officials reviewed the accounting report in detail with the KPMG partner in charge of it, Andrew Gersh, who didn’t raise any serious concerns.

In a statement, KPMG said, “We stand behind our work and our report, but beyond that our professional obligations and client confidentiality agreements prevent us from speaking in any greater detail.”

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James B. Stewart, on CNBC, discussed the leadership skills of top executives at Hewlett-Packard, including Carly Fiorina and Léo Apotheker.

On at least two occasions, Aug. 16, before the deal was announced, and Sept. 4, after the deal was announced and investors punished H.P.’s stock price, Mr. Lane, the board chairman, expressed serious reservations. In an email to Mr. Apotheker, Mr. Lane wrote that he was “haunted” by Autonomy, was worried that it was a “roll up,” (meaning that growth came through acquisitions) and asked if H.P. could get out of the deal. “I don’t think it’s the panacea we think it is,” he wrote.

Mr. Apotheker’s reply hasn’t been disclosed, but according to people who have seen it, he assured Mr. Lane that Autonomy had legitimate organic growth. H.P.’s lawyers also said it was extremely difficult to back out of a signed and announced deal under British law.

But the KPMG report surely provided enough evidence — Autonomy’s refusal to back up its assertions with documents, as well as KPMG’s warning that Autonomy’s organic growth was declining and revenue growth came in large part through acquisitions, just as Mr. Lane feared — to renegotiate or cancel the deal before it was announced.

According to Professor Elson, “The KPMG report could have been a road map out of the deal.” The lack of cooperation “was stressed so high in the executive summary, which makes it clear that they needed to do a deeper dive,” he said. “That’s the whole point of due diligence. If it raises questions, you have the right to restructure the deal or walk away. You don’t buy a pig in a poke. You certainly shouldn’t pay $11 billion to buy a pig in a poke.”

As it turned out, it was only after the deal closed that H.P. discovered what it now maintains was a huge fraud on the part of Autonomy’s top executives, including Autonomy’s chief executive, Michael Lynch, and its chief financial officer, Sushovan Hussain. Even then, it took a whistle-blower and nearly six months of intensive forensic accounting work for H.P. to piece together its claims.

“No amount of due diligence could have uncovered that for more than two years prior to HP’s acquisition of Autonomy, Mike Lynch and Sushovan Hussain conducted a systematic and sustained scheme to make Autonomy look like a rapidly growing, pure software company whose performance was consistently in line with market expectations,” an H.P. spokeswoman, Sarah Pompei, said this week.

In March, H.P. accused Mr. Lynch and Mr. Hussain of fraud in a lawsuit filed in Britain. The company is seeking $5.1 billion in damages. Mr. Lynch has denied the accusations and promptly countersued for $150 million, accusing H.P. of false and negligent statements. A federal grand jury continues to hear evidence in the Justice Department’s criminal investigation of H.P.’s accusations against the former Autonomy executives.

For its part, H.P. has revised its requirements for merger due diligence, including the formation of a senior-level risk management committee and greater involvement of the board’s finance and investment committee.

Meanwhile, the question persists: In light of these disclosures, can Ms. Fiorina really be considered a worse chief executive than Mr. Apotheker? I posed the question this week to Professor Sonnenfeld, whose criticism Ms. Fiorina has dismissed as coming from a longtime friend and adviser to Bill Clinton.

“Apotheker’s reign was terrible, but still not as destructive as Fiorina’s reign of terror,” Professor Sonnenfeld maintained. “The magnitude of the damage from the Compaq deal was greater, both culturally and financially, than Autonomy. And at least they got rid of Apotheker and wrote off Autonomy right away. Compaq lingered for a tortured decade.”

A version of this article appears in print on , Section B, Page 1 of the New York edition with the headline: A Deal That Still Haunts Hewlett-Packard. Order Reprints | Today’s Paper | Subscribe